1. Field of the Invention
The present invention relates to a technique suitable for use in a system which authenticates the identity of a person by means of biometric information (biometrics information); for example, a fingerprint, a palm pattern, an iris (iris muscle pattern), a voice, a facial image, a vascular pattern (a retinal vascular pattern, or a vein pattern), a dynamic signature, or a keystroke.
2. Description of the Related Art
Recently, in association with extensive introduction of a computer into society, attention has been focused on security. An ID card or a password has hitherto been used as identification means when a person enters a computer room or makes use of a terminal. However, these means have many security problems.
For this reason, biometrics authentication utilizing biometric information about a human has recently been put into widespread use as identification means which is more reliable than the ID card or the password. For instance, a fingerprint, a palm pattern, an iris, a facial image, a voice, a vascular pattern, a dynamic signature, or a keystroke is used as biometric information. Commercialization of a biometric authentication technique utilizing a fingerprint among these pieces of biometric information has been pursued most extensively.
One-to-one authentication is usually used for fingerprint authentication. Specifically, a subject of authentication enters an ID, such as a user name, and a fingerprint as well. Registered fingerprint data, which have been registered beforehand, are read in association with the ID, and personal authentication is performed by verifying the registered fingerprint data against the fingerprint data input by the subject of authentication. However, such one-to-one authentication requires a keyboard and a keypad used for inputting an ID, as well as a fingerprint sensor, thus requiring equipment cost. Further, there also exists strong demand for reducing the effort required when the subject of authentication inputs an ID.
In contrast, an authentication technique for specifying a person by inputting only a fingerprint without inputting an ID is called one-to-many authentication. According to this one-to-many authentication, the fingerprint data input by the subject of authentication are verified against all of the fingerprint data sets that have been registered in advance to thus specify fingerprint data coinciding with the input fingerprint data from among the registered fingerprint data, thereby authenticating the subject. However, according to such one-to-many authentication, an increase in the number of registered fingerprint data sets naturally entails an increase in the time required to verify all the registered fingerprint data against input fingerprint data. For this reason, shortening of the verification time is desired.
A technique for minimizing an increase in the verification time required for one-to-many authentication is described in, e.g., Japanese Patent Laid-Open NO. 2002-133416 (hereinafter called Patent Document 1). According to the technique disclosed in Patent Document 1, attribute information (e.g., a fingerprint pattern type: see FIG. 6A to FIG. 6H) other than fingerprint data used for verification is detected. The registered fingerprint data have been classified in advance by means of the attribute information. Input fingerprint data are verified against registered fingerprint data that have the same attribute information (a pattern type) as that obtained from the subject of authentication during authenticating operation. However, when, for instance, a fingerprint pattern type is used as attribute information, the registered fingerprint data can be classified only into the number “n” of fingerprint-type groups (e.g., eight types shown in FIGS. 6A to 6H) by means of such a technique. Therefore, the shortening of verification time is limited to a factor of only to about one-nth.
The present invention has been conceived in view of this problem and realizes significant shortening of the time required to verify input feature information against registered feature information when one-to-many authentication is performed through use of biometric information.